In July, we announced a roughly 2% increase in our common stock dividend effective later this month, thus making 2021 our 32nd consecutive year of annual dividend increases.
National Retail Properties is in the select company of only 85 U.S. public companies, including only two other REITs, which have achieved this impressive track record.
Based on our strong performance, we announced today a further increase in our 2021 guidance for core FFO per share to a range of $2.75 to $2.80 per share.
Our portfolio of 3,173 freestanding single-tenant retail properties continue to perform exceedingly well.
Occupancy was consistent with the prior quarter at 98.3%, which remains above our long-term average of 98%.
We also announced collection of 99% of rents due for the second quarter.
Mister Car Wash was one of our first relationship tenants 15 years ago, and we're very proud of the role that National Retail Properties has played in that company's growth and success.
During the quarter, we invested just under $103 million in 29 new properties at an initial cash cap rate of 6.7% and with an average lease duration of over 17 years.
Year-to-date, we've invested over $208 million in 58 new properties leased to 10 different relationship tenants at an initial cash cap rate of 6.5% and an average lease duration of 17.5 years.
Based on our pipeline and conversations with those relationship tenants, we remain comfortable with our ability to meet and hopefully exceed our 2021 acquisition guidance of $400 million to $500 million, primarily via direct sale-leaseback transactions with long duration leases.
During the second quarter, we also sold 15 properties, raising almost $23 million of proceeds to be reinvested in new acquisitions.
And year-to-date, we've now raised over $40 million from the sale of 26 properties, including 15 vacant properties.
In June, Kevin led the recast of our unsecured line of credit, increasing the capacity of our facility from $900 million to $1.1 billion.
Although our credit line has been upsized, the balance outstanding remains the same, 0, and we ended the quarter with approximately $250 million of cash on hand.
That's up $0.01 from the preceding first quarter, $0.69 per share, and it's up $0.05 from the prior year's $0.65.
Today, we also reported that AFFO per share was $0.77 per share for the second quarter and that's also up $0.01 from the preceding first quarter $0.76.
We did footnote this amount includes $8.3 million of deferred rent repayments and our accrued rental income adjustment in the second quarter AFFO number.
So without that, we would have produced AFFO of $0.72 per share.
So excluding those deferral repayments, our AFFO dividend payout ratio for the first six months was 72.7%, that's fairly consistent with prior year's levels.
Occupancy, as Jay mentioned, was 98.3% at quarter end.
G-and-A expense was $11.9 million for the second quarter.
As Jay mentioned, today, we reported rent collections of approximately 99% for the second quarter rent.
Collections from our cash basis tenants, which represent about 7% of our total annual base rent improved to approximately 92% for the second quarter rent, and that's up from 80% previously reported for that cohort in the first quarter of 2021.
As Jay noted, we increased our 2021 core FFO per share guidance from a range of $2.70 to $2.75 per share to a new range of $2.75 to $2.80 per share.
So while we previously assumed 80% rent collection from the $50 million of cash basis tenant annual base rent, we are now assuming 90% rent collections that incremental 10% amounts to about $5 million on an annual basis.
And for the remainder of our tenants, we continue to assume 1% of potential rent loss.
We ended the quarter with $250 million of cash on hand and no amounts outstanding on our newly recast $1.1 billion bank credit facility.
This bank line, as Jay noted, increased from $900 million in size to $1.1 billion.
The interest rate was reduced 10 basis points to LIBOR plus 77 basis points and maturity was extended to June of 2025.
Our liquidity is in excellent shape, our weighted average debt maturity is now 13 years with a 3.7% weighted average fixed interest rate.
Our next debt maturity is $350 million with a 3.9% coupon in mid-2024.
Net debt to gross book assets was 35%.
At quarter end, net debt to EBITDA was 5.0 times at June 30.
Interest coverage, 4.7 times and fixed charge coverage 4.2 times for the second quarter.
Only five of our 3,000-plus properties are encumbered by mortgages.

Summary:
Today, we also reported that AFFO per share was $0.77 per share for the second quarter and that's also up $0.01 from the preceding first quarter $0.76.
As Jay noted, we increased our 2021 core FFO per share guidance from a range of $2.70 to $2.75 per share to a new range of $2.75 to $2.80 per share.