We achieved depletions growth of 26% in the fourth quarter and 37% for the full year.
In 2020, Truly increased its market share in measured off-premise channels from 22 points to 26 points and was the only national hard seltzer, not introduced in 2020, to grow share.
Based on information in hand, year-to-date depletions reported to the company through the 6 weeks ended February 6, 2021 are estimated to increase approximately 53% from the comparable weeks in 2020.
For the fourth quarter, the reported net income of $32.8 million or $2.64 per diluted share, an increase of $1.52 per diluted share or 136% from the fourth quarter of last year.
Shipment volume was approximately 1.94 million barrels, a 54% increase from the fourth quarter of 2019.
The Company believes distributor inventory as of December 26, 2020 averaged approximately 5 weeks on hand and was at an appropriate level, based on supply chain capacity constraints and inventory requirements to support the forecasted growth.
Our fourth quarter 2020 gross margin of 46.9% decreased from the 47.4% margin realized in the fourth quarter of last year, primarily as a result of higher processing costs due to increased production at third party breweries, partially offset by cost saving initiatives at Company-owned breweries and price increases.
Fourth quarter advertising, promotional and selling expenses increased $48.1 million from the fourth quarter of 2019, primarily due to increased investments in media and production, increased salaries and benefits costs and increased freight to distributors because of higher volumes.
General and administrative expenses were flat from the fourth quarter of 2019, primarily due to non-recurring Dogfish Head transaction-related expenses of $2.1 million incurred in the comparable 13-week period of 2019, partially offset by increases in salaries and benefits costs.
Our full-year net income per diluted share of $15.53 increased $6.37 or 70% compared to the prior year.
Our full-year 2020 shipment volume was approximately 7.37 million barrels, a 38.8% increase from the prior year.
Based on information of which we are currently aware, we are targeting 2021 earnings per diluted share of between $20 and $24, but actual results could vary significantly from this target.
This projection excludes the impact of ASU 2016-09.
We are currently planning increases in shipments and depletions of between 35% and 45%.
We're targeting national price increases per barrel of between 1% and 2%.
Full year 2021 gross margins are currently expected to be between 45% and 47%, a decrease from the previously communicated estimate of between 46% and 48%.
We plan increased investments in advertising promotional and selling expenses of between $120 million and $140 million for the full year 2021, a decrease from the previously communicated estimate of between $130 million and $150 million, not including any increases in freight costs for the shipment of products to our distributors.
We estimate our full-year 2021 effective tax rate to be approximately 26.5%, excluding the impact of ASU 2016-09.
We are not able to provide forward guidance on the impact of ASU 2016-09 will have on our 2021 financial statements and full-year effective tax rate, as this will mainly depend upon unpredictable future events including the timing and value realized upon exercise of stock options versus the fair value of those options were granted.
We are continuing to evaluate 2021 capital expenditures and currently estimate investments of between $300 million and $400 million.

Summary:
For the fourth quarter, the reported net income of $32.8 million or $2.64 per diluted share, an increase of $1.52 per diluted share or 136% from the fourth quarter of last year.