With record occupancy of 94% at quarter end, we have managed to grow occupancy by 460 basis points year-over-year, an incredible accomplishment, and I'm very proud of the entire Life Storage team.
With this level of occupancy, we have been aggressively pushing asking rates while also decreasing free rent, resulting in higher net effective rates, which were up roughly 20% for the quarter.
Further, we have been very active on the acquisition front, with 33 stores acquired or under contract since the beginning of the year.
We also continue to see strong growth in our third-party platform with 18 new additions during the quarter and a very robust pipeline as more and more owners consider Life Storage as a leading candidate to manage their stores.
We are raising the midpoint of our estimated adjusted funds from operations per share by more than 3% to $4.37 this year, which would be 10.1% growth over 2020.
Last night, we reported adjusted quarterly funds from operations of $1.08 per share for the first quarter, an increase of 16.1% year-over-year.
First quarter same-store revenue accelerated significantly again to 7.3% year-over-year, up 240 basis points from the 4.9% growth produced in the fourth quarter.
Revenue performance was driven by a 410 basis point increase in average quarterly occupancy.
In the quarter, our move-ins were paying almost 6% more than our move-outs, which is a significant improvement from the rent roll down that we experienced in the same quarter last year.
Our move-ins have been paying more than our move-outs for six straight months, with March move-ins paying almost 8% more than move-outs.
Same-store operating expenses increased 4.7% year-over-year for the quarter.
Payroll and benefits, again, remained well controlled, up only 1.8% year-over-year, while advertising and Internet marketing costs were down 2.6%.
The net effect of the same-store revenue and expense performance was an increase in net operating income of 8.6% for the quarter.
We supported our acquisition activity and liquidity position by issuing approximately $180 million of common stock via our ATM program in the first quarter.
Our net debt to recurring EBITDA ratio decreased to 5.5 times, and our debt service coverage increased to a healthy 4.9 times at March 31.
At quarter end, we have $457 million available on our line of credit, and we have no significant debt maturities until April of 2024 when $175 million becomes due.
Our average debt maturity is 6.7 years.
Specifically, we expect same-store revenue to grow between 5.5% and 6.5%.
Excluding property taxes, we continue to expect other expenses to increase between 2.25% and 3.25%, while property taxes are expected to increase 6.75% to 7.75%.
The cumulative effect of these assumptions should result in 6.5% to 7.5% growth in same-store NOI relative to our original guidance of between 3.75% and 4.75%.
We have also increased our anticipated acquisitions by $175 million to between $550 million and $600 million.
Based on these assumptions changes, we anticipate adjusted FFO per share for the 2021 year to be between $4.33 and $4.41.

Summary:
Last night, we reported adjusted quarterly funds from operations of $1.08 per share for the first quarter, an increase of 16.1% year-over-year.
First quarter same-store revenue accelerated significantly again to 7.3% year-over-year, up 240 basis points from the 4.9% growth produced in the fourth quarter.
Based on these assumptions changes, we anticipate adjusted FFO per share for the 2021 year to be between $4.33 and $4.41.