And as part of those efforts Piedmont and its related foundation has donated over $40,000 to local charities across all our seven markets including Seniors First in Orlando, NYU Langone hospital in New York City; Meals on Wheels in Northern Virginia, and the Emory Hospital COVID-19 impact fund here in Atlanta, among others.
We feel fortunate to have limited exposure to some of the industry's most disrupted about 1% of our forecasted 2020 revenues are related to retail tenants and likewise, about 2% of our 2020 budgeted revenues are associated with the co-working sector.
So far Piedmont has had 96% of it's tenants submit full rent payment, with many of the remaining seeking some form of rent deferral for the month of April.
Piedmont also has a favorable liquidity position with access to our largely unused $500 million line of credit.
Further, bolstering our liquidity, we have entered into a binding contract to sell our only asset in Philadelphia, 1901 Market Street for $360 million.
We intend to use the proceeds from the sale to repay the properties $160 million mortgage, as well as eliminate the balance on our line of credit, which will result in only one small mortgage remaining in our portfolio, where the other 56 properties being unencumbered.
During the quarter we completed approximately 417,000 square feet of leasing, which as well as first across all our operating markets and included approximately 120,000 square feet of new tenant leasing.
The first quarter execute leases for recently occupied space reflected a 5% roll up in cash rents and a 15.4% increase in accrual rents.
The larger leases for the quarter include the following: In Boston, Advanced Micro Devices renewed to 2028, approximately 107,000 square feet at 90 Central Street.
In Orlando the law firm at Greenberg Traurig renewed approximately 37,000 square feet to the year 2031 at CNL Center I and at 200 South Orange Avenue; Jones Lang LaSalle signed a renewal expansion through 2026 totaling approximately 20,000 square feet.
Finally in Washington, the Association for Unmanned Vehicle Systems signed a new lease through the end of 2030 for approximately 15,000 square feet at 3100 Clarendon Boulevard.
As of quarter end, the portfolio was approximately 90% leased.
The leased percentage at the end of the quarter includes the transfer into service of our previously out of service asset, the recently redeveloped now 41% lease to [Indecipherable] Tower in Chicago.
Regarding upcoming lease expirations we have low lease expiration over the next 18 months with the only sizable lease being the City of New York at 60 Broad Street, where we remain in discussions for a long-term renewal of substantially all the cities existing 313,000 square foot lease that expired this month.
Turning to transactional activity, as we previously announced during the first quarter, we completed the depth purchase in Dallas, Texas, of the Galleria Office Towers, comprising 1.4 million square feet and an adjacent two acre development parcel for a total of $396 million or approximately $273 per square foot, which represents a significant discount to replacement cost.
The Galleria Office Towers required to reverse exchange and we match for the disposition of 1901 Market Street in Philadelphia that is expected to close in the middle of the summer.
For the first quarter of 2020, we reported $0.47 per diluted share of core FFO, that's a $0.02 increase, compared to the first quarter of 2019.
Even with the loss of earnings contribution due to dispositions up to almost fully leased assets during 2019 that's the One Independence Square building in Washington, DC and our 500 West Monroe property in Chicago, we were more than able to offset these sales with newly acquired Sun Belt properties in Atlanta and Dallas, as well as with new lease commitments and with the continued roll-up of rents across the portfolio.
AFFO was approximately $19 million for the first quarter, which is lower than typical and impacted by one-time payment of lease commissions on a 520,000 square foot 20-year lease to the State of New York at 60 Broad Street in New York City.
With several leases commencing in Atlanta and in Houston late last year, same-store NOI was approximately 2% on a cash basis and 4% on an accrual basis for the first quarter of 2020.
Turning to the balance sheet, our average net debt core EBITDA ratio for the first quarter of 2020 was 5.7 times and our debt to gross asset ratio was approximately 38.7% at the end of the quarter.
During the quarter, we entered into a new $300 million unsecured term loan and used the proceeds to pay down our $500 million line of credit, leaving approximately $350 million of availability.
As Brent mentioned earlier, we plan to pay off the remaining balance on the line, as well as our $160 million mortgage [Technical Issues] the proceeds from the sale of 1901 Market Street, which is expected to close this summer.
We are withdrawing our guidance for 2018.
While we continue to execute lease renewals, new tenant leasing activity during the second quarter has been slow and we think this trend will continue throughout the quarter, likely pushing all new tenant leasing goals out at least a quarter which will, in all likelihood modestly lower annual operating revenues for 2020 by $1 million to $2 million and lower our originally anticipated year-end leased percentage.
We expect most of our transient parking income for the second quarter will not occur, that would equate to a reduction of approximately $1 million of net operating income.
And with respect to retail tenant income, which is about 1% of our total 2020 revenues, retail NOI is estimated to decline by approximately $1.5 million.
The sale of 1901 Market Street in Philadelphia is expected to close during the summer and while no other deals are under way any other acquisition or disposition during the year will be pricing, property and market dependent.
Now as Brent noted for the month of April to-date, we've received 96% of our regular monthly rents, with all of our 20 largest tenants representing over a third of our cash receipts paying their April rents.
Of the unpaid 4$amount we do have the number of tenants requesting their leases the restructure.
To date, we've agreed to about $1 million of rent deferrals per month for three months for 27 of our tenants, representing approximately 400,000 square feet of leases.
Regarding our seven tenants in the co-working sector all the one are under traditional lease structures with standard credit requirements and combined total about 2% of our originally forecasted revenues.

Summary:
For the first quarter of 2020, we reported $0.47 per diluted share of core FFO, that's a $0.02 increase, compared to the first quarter of 2019.
During the quarter, we entered into a new $300 million unsecured term loan and used the proceeds to pay down our $500 million line of credit, leaving approximately $350 million of availability.
We are withdrawing our guidance for 2018.