The issue of erecting barriers at the U.S.-Mexico border hasn’t always been the subject of a full-throated debate in the Oval Office, as it was on Tuesday.

President Donald Trump has asked for $5 billion and the Democrats have countered with a $1.3 billion offer for border security, which resulted in a three-way public debate between Trump, Senate Minority Leader Chuck Schumer and House Minority Leader Nancy Pelosi.

But the U.S. has been spending money long before Trump took that famous escalator ride down his eponymous tower, and Taxpayers for Common Sense, a budget watchdog group, has tabulated the bill.

Since 2007, the U.S. has spent $9.7 billion on border barrier construction, almost entirely at the Southwest border, the group says.

Customs and Border Protection first started erecting barriers in 1990, in San Diego. Between 2005 and 2011, the government started constructing several hundred miles of new barriers, before adopting a strategy that relies more on patrols and interdiction.

The White House itself estimates a full wall along the border would cost $25 billion, while other studies put the tab at around $40 billion.