Numbers to know: Midtown East has cheapest asking prices in Gotham, Obama’s former UWS pad for rent … and more

“Numbers to know” is a weekly web feature that catalogues the most notable, quirky and surprising real estate statistics. Thrifty homebuyers should check out Midtown East for deals, a look at the year in luxury real estate so far and President Barack Obama’s former Upper West Side apartment is back on the rental market.

$7.5 billion
Dollar volume of Manhattan residences asking over $4 million — 962 properties — that has gone into contract this year [Olshan Luxury Market Report]

210,000
Residents in Rochester, N.Y., which last week won New York State Department of Health’s prize for the best drinking water in the state; New York City was one of the top 10 finalists [DOH]

$2,400
Monthly rent of President Barack Obama’s former Upper West Side apartment, which is back on the rental market — he paid $360 a month for the two-bedroom, one-bathroom prewar pad back in 1981 [Zillow]

255
Contracts signed over $5 million in the second quarter of 2013 — only 126 were signed in the same quarter last year [Corcoran Sunshine]

$910
Average asking price per square foot in Midtown East — the neighborhood with the cheapest asking prices for Manhattan apartments in August [Maxwell Jacobs]

63
Percentage of potential homebuyers nationwide that said rising mortgage rates were making it more difficult for them to afford a home [Redfin]

16
Basis point increase in New York’s mortgage rates, which increased to 4.53 percent in the week ending Sept. 3, from 4.37 percent in the week ending Aug. 27 — the biggest increase of any state in the country [Zillow]

6
Weeks luxury rental development 101 Bedford in Williamsburg has been on the market; 70 percent of its first two buildings’ 174 units are already leased [101 Bedford]

5
Units in the new condominium conversion at 364 Union Street in Carroll Gardens, which launched sales last week [Halstead Property Development Marketing]