Briefly reviewing our operating results for the 4th quarter, revenue grew 10% as reported, 7% on a constant currency basis and adjusted, adjusted earnings per share grew 14%.
For the full year, revenue declined 2% and adjusted earnings per share was up 1%.
Our largest market category pharma was the primary growth driver in the quarter with 15% growth.
Our industrial market grew 5% while academia and government declined 15%.
On a constant currency basis, sales in Asia were up 12% with China, up 19%.
Meanwhile, sales in the Americas grew 3% for the US growing 4% and European sales grew at 6%.
From a product perspective, our Waters branded products and services grew approximately 8% while TA declined by around 1% on a constant currency basis.
Services grew 10% while consumables business grew approximately 14% driven largely by global pharma strength, including sales of our recently launched PREMIER Columns, which performed exceedingly well in the first quarter on the market.
Combined these, comprised approximately 10% to 15% of TA's total revenues.
Now for the year, our pharmaceutical market category achieved 1% growth with the US, Europe, and India all seeing positive growth.
Industrial declined 3% for the full year and academic and government declined 16%.
Notably, our pharma market category grew 10% in the second half compared to the first half decline of 8% owed in part to strength in small molecules, the industry recovered from lock-downs.
Industrial also grew in the second half at 4% while academic and government declined 12% compared to the first half declines of 10% and 22% respectively.
Geographically for the year, Asia sales were down 4% with China -- China sales down 8%.
Sales in Americas were down 4%; for the US, down 2%.
Europe sales were up 2%.
Notably, all our major geographies grew in the second half of the year with the US up 4% and Europe up 6% following first half declines of 9% and 3% respectively.
China market grew in the second half, up 11%, reversing much of its sharp 31% decline in the first half of the year.
This peaked in the 4th quarter were COVID revenues contributed an estimated 1 to 2 percentage points to the growth, driven by those pharmaceutical customers developing COVID vaccines and therapeutics who saw meaningfully higher growth than manufacturers that don't have COVID-related programs.
In the 4th quarter, we recorded net sales of $787 million, an increase of approximately 7% in constant currency.
Currency translation increased sales growth by approximately 3% resulting in sales growth of 10% as reported.
For the full year, sales declined about 2% in constant currency and as reported.
Looking at product line growth, our reoccurring revenue, which represents the combination of precision chemistry products and service revenue increased by 11% in the quarter while instrument sales increased 4%.
For the full year, reoccurring revenue grew 3% while instrument sales declined 9%.
Chemistry revenue were up 14% in the quarter, driven by strong pharma growth.
On the service side of our business, revenues were up 10%, as customers continue to reopen labs, catch up on performance maintenance in professional services, and repair visits.
Breaking 4th quarter product sales down further, sales related to Waters' branded products and services grew 8% while sales of TA-branded products and services declined 1%.
Combined LC and LCMs instrument sales were up 5% while TA system sales declined 4%.
Gross margin for the quarter was 59.2%, an increase compared to the 58.2% in the 4th quarter of 2019, primarily due to the higher sales volume in FX.
On non -- on a full year basis, gross margin was 57.4% compared to 58% in the prior year on lower overall sales volumes in 2020.
Moving down the 4th quarter P&L, operating expenses increased by approximately 6% on a constant currency basis and 8% on a reported basis.
For the year, operating expenses were 1% lower before currency translation and flat after.
In the quarter and for the full year, our effective operating tax rate was 14.9% and 14.8% respectively, an increase from last year at the comparable period included some favorable discrete items.
Net interest expense was $7 million for the quarter, a decrease of about 3 million, as anticipated on lower outstanding debt balances.
Our average share count came in at 62.5 million shares, a reduction of approximately 3% or about 2 million shares lower than in the 4th quarter of last year.
Our non-GAAP earnings per fully diluted share for the 4th quarter increased 40% to $3.65 in comparison to the $3.20 last year.
On a GAAP basis, our earnings per fully diluted share increased to $3.49 compared to $3.12 last year.
For the full year, our non-GAAP earnings per fully diluted share were up 1% at $9.05 per share versus $8.99 last year.
On a GAAP basis, full year earnings per share were $8.36 versus $8.69 in 2019.
In the 4th quarter of 2020, free cash flow grew 52% year-over-year to $240 million after funding $47 million of capital expenditures.
Excluded from free cash flow was $19 million related to the investment in our Taunton precision chemistry operation.
In the 4th quarter, this resulted in $0.30 of each dollar of sales converted into free cash flow.
For the full year in 2020, free cash flow generation was $726 million after funding $172 million of capital expenditures.
This represents a 26% increase and $0.31 per dollar of sales converted into free cash flow.
Excluded from free cash flow was $70 million related to our investment in our Taunton chemistry operations and a $38 million transition tax payment related to the 2017 US tax reform.
In the 4th quarter, accounts receivables days sales outstanding came in at 70 days, down seven days compared to the 4th quarter of last year.
Inventories decreased by 16 million in comparison to the prior quarter -- prior year quarter, reflecting stronger revenue growth in revised production schedules.
We ended the quarter with cash and short-term investments of $443 million and debt of 1.4 billion on our balance sheet at the end of the quarter.
This resulted in a net debt position of $913 million and a net debt to EBITDA ratio of about 1.1 times at the end of the 4th quarter.
As of today, we have 1.5 billion remains available credit program for share repurchases.
We had a 1% tailwind from COVID-related revenue in 2000, three-quarters of which was in the second half of the year.
We expect a similar revenue impact in 2021, including a 1% to 2% growth tailwind in Q1.
These dynamics support full-year 2021 guidance for constant currency sales growth of 5% to 8%.
At current rates, the positive currency translation to 2021 sales growth is expected to be 1 to 2 percentage points.
Gross margin for the full year is expected to be in the range of 57, 5% to 58.9%.
Accordingly, we expect 2021 operating margins of 28% to 29% based on a combination of growth investments, normalization of COVID-related cost actions, and disciplined expense controls.
Moving now below the operating income line, other key assumptions for full-year guidance are net interest expense of 35 million to 38 million, a full year tax rate of between 15% and 16%, which includes our new five-year tax agreement with Singapore that will expire in March 2026, a restart of our share repurchase program in 2021 that will result in an average diluted 2021 share count of 61 to 61.5 million shares outstanding.
Rolling all of this together and on a non-GAAP basis, full year 2021 earnings per fully diluted share are projected in the range of $9.32 to $9.57, which assumes a positive currency impact on full year earnings-per-share growth of approximately 3 percentage points.
Looking at the first quarter of 2021, we expect constant currency sales growth to be 7% to 10%.
At today's rate, currency translation is expected to increase first quarter sales growth by approximately 3 percentage points.
First quarter non-GAAP earnings per fully diluted share are estimated to be in the range of $1.50 to $1.60.
At current rates, the positive currency impact on first quarter earnings-per-share growth is expected to be approximately 15 percentage points.

Summary:
Briefly reviewing our operating results for the 4th quarter, revenue grew 10% as reported, 7% on a constant currency basis and adjusted, adjusted earnings per share grew 14%.
In the 4th quarter, we recorded net sales of $787 million, an increase of approximately 7% in constant currency.
Our non-GAAP earnings per fully diluted share for the 4th quarter increased 40% to $3.65 in comparison to the $3.20 last year.
On a GAAP basis, our earnings per fully diluted share increased to $3.49 compared to $3.12 last year.
These dynamics support full-year 2021 guidance for constant currency sales growth of 5% to 8%.
Rolling all of this together and on a non-GAAP basis, full year 2021 earnings per fully diluted share are projected in the range of $9.32 to $9.57, which assumes a positive currency impact on full year earnings-per-share growth of approximately 3 percentage points.
Looking at the first quarter of 2021, we expect constant currency sales growth to be 7% to 10%.
At today's rate, currency translation is expected to increase first quarter sales growth by approximately 3 percentage points.
First quarter non-GAAP earnings per fully diluted share are estimated to be in the range of $1.50 to $1.60.