During the second quarter of fiscal-year 2021, we generated over $170 million of cash, allowing us to return over $57 million in dividends to shareholders.
We have an exciting pipeline of innovative solutions that will generate both medium and long-term value for our customers, with an industry-leading IP portfolio, including over the 6,000 patents and designs.
We now have over 8 billion nights of respiratory medical data in our cloud-based Air Solutions Platform.
We have sold over 13.5 million 100% cloud connectable medical devices into the market from ResMed, and we have over 15 million patients enrolled in our AirView Solutions in the cloud.
To be clear, the spectrum of chronic diseases that we look out here at ResMed are, of course, including our core focus areas of sleep apnea, COPD, and asthma, but it also includes biological systems interaction with cardiovascular disease, with cancer, with type 2 diabetes, with neuromuscular disease, Alzheimer's and beyond.
We're seeing 70% to 90% of the pre-COVID patient flow coming through our biggest market in the United States, and to take an example of a European country, in Germany, we're already back to 85% to 90-plus percent in some states of Germany of pre-COVID patient flow.
Even in countries like China, in our large Asia region, where we saw the sharpest declines at the start of this crisis with very severe lockdowns in Asia and particularly in China, we're now back to already seeing around 70-plus percent, 70% to 75% of pre-COVID patient flow coming through the mainly hospital clinics in our China market.
It also showed the converse side in that not treating sleep apnea leads to a significantly higher incidence of heart attack, type 2 diabetes, and ischemic heart disease, leading to significantly higher healthcare costs treating those diseases and ultimately leading to earlier death.
We make the smallest, quietest, and most comfortable devices on the market and they are all 100% cloud connectable.
We entered the POC market in 2016 as a way to engage with Stage 2 and Stage 3 COPD patients.
Since then, in these last five years, we have acquired Propeller, giving us access to COPD patients even earlier in their COPD disease progression, including Stage 1 and Stage 2 COPD patients.
We have pharmaceutical drug delivery management through Propeller to support COPD patients in Stage 1 and Stage 2 COPD, we have the emergence of high flow therapy for Stage 2 and Stage 3 COPD and we have growing use of noninvasive ventilation and life support ventilation to support patients in Stage 3 and Stage 4 COPD.
We were able to pivot our whole team and our HOT business to provide over 150,000 ventilators during the peak needs of the pandemic and get them to where they needed based upon a humanitarian epidemiology model.
And that's where ResMed competes for more than 90% of our business.
With over 1.5 billion people worldwide suffering from sleep apnea, COPD, and asthma combined, we see incredible opportunities for greater and greater adoption of these scalable technologies.
We are poised to continue relentless innovation and development, as well as to provide the global scale that's needed to drive this technology to the 140 countries that we operate in and beyond.
Before I hand the call over to Brett for his remarks, and then we get to the Q&A, I want to once again express my sincere genuine gratitude to the more than 7,500 ResMedians, whose perseverance, hard work, and dedication during the incredibly challenging circumstances of 2020 allowed our partners in healthcare to save the lives of many hundreds of thousands of people around the world with emergency need for ventilation, literally given the gift of breath and the gift of life to many during COVID.
Group revenue for the December quarter was $800 million, an increase of 9% over the prior-year quarter.
In constant-currency terms, revenue increased by 7%.
Taking a closer look at our geographic distribution and excluding revenue from our Software as a Service business, our sales in U.S., Canada, and Latin America countries were $427 million, an increase of 5%.
Sales in Europe, Asia, and other markets totaled $281 million, an increase of 17%, growing constant-currency terms an increase of 10%.
By product segment, U.S., Canada, and Latin America device sales were $205 million, an increase of 1%.
Masks and other sales were $222 million, an increase of 8%.
In Europe, Asia, and other markets, device sales totaled $188 million, an increase of 16% or in constant-currency terms, a 10% increase.
Masks and other sales in Europe, Asia, and other markets were $93 million, an increase of 18% or in constant-currency terms, an increase of 12%.
Globally, in constant-currency terms, device sales increased by 5%, while masks and other sales increased by 9%.
Software as a Service revenue for the second quarter was $92 million, an increase of 6%.
On a non-GAAP basis, SaaS revenue increased by 5%.
Our non-GAAP gross margin improved by 20 basis points to 59.9% in the December quarter compared to 59.7% in the same quarter last year.
Our SG&A expenses for the second quarter were $169 million, a decrease of 1% or in constant-currency terms, SG&A expenses decreased by 3%.
SG&A expenses as a percentage of revenue improved to 21.2% compared to the 23.3% we reported in the prior-year quarter.
R&D expenses for the quarter were $55 million, an increase of 10% or on a constant-currency basis, an increase of 7%.
R&D expenses as a percentage of revenue was 6.9% compared to 6.8% in the prior year.
Total amortization of acquired intangibles was $19 million for the quarter and stock-based compensation expense for the quarter was $15 million.
Non-GAAP operating profit for the quarter was $254 million, an increase of 16%, reflecting strong top-line growth, expansion of gross margins, and well-contained operating expenses.
On a GAAP basis, our effective tax rate for the December quarter was 14.8%, while on a non-GAAP basis, our effective tax rate for the quarter was 15.2%.
We continue to expect our effective tax rate for the full fiscal-year 2021 will be in the range of 17% to 19%.
Non-GAAP net income for the quarter was $206 million, an increase of 17%.
Non-GAAP diluted earnings per share for the quarter were $1.41, also a 17% increase.
Our GAAP diluted earnings per share for the quarter were $1.23.
We recognized that restructuring expenses of $13.9 million associated with the closure.
Cash flow from operations for the quarter was $170 million, reflecting robust underlying earnings, partially offset by increases in working capital.
Capital expenditure for the quarter was $35 million.
Depreciation and amortization for the December quarter totaled $41 million.
During the quarter, we paid dividend of $57 million.
We recorded equity losses of $2.6 million in our income statement in the December quarter associated with the Verily joint venture.
We expect to record equity losses of approximately $5 million per quarter in the second half of FY '21 associated with the joint venture operations.
We ended the second quarter with a cash balance of $256 million.
At December 31, we had $826 million in gross debt and $570 million in net debt.
At December 31, we had a further $1.4 billion available for drawdown under our existing revolver facility.
Our board of directors today declared a quarterly dividend of $0.39 per share, reflecting the board's confidence in our strong liquidity position and operating performance.
Note, as a reminder, we recorded $35 million in COVID-generated ventilator revenue in our March quarter last year and $125 million in COVID-generated ventilator revenue in our June quarter last year.

Summary:
Group revenue for the December quarter was $800 million, an increase of 9% over the prior-year quarter.
Non-GAAP diluted earnings per share for the quarter were $1.41, also a 17% increase.
Our GAAP diluted earnings per share for the quarter were $1.23.