(Denver Mint issues are comparatively scarce). They are seen in two varieties: 1) with both edge lettering inscriptions reading in the same direction, called "overlapped", and 2) with the two inscriptions running in opposite directions—i.e., inverted or upside-down relative to one another—called "inverted". In early March 2007, a Colorado couple found a dollar coin which had not been struck with a die pair (missing the portrait of the president and the Statue of Liberty), but with edge lettering on the otherwise-blank planchet. Some of the coins have the words on the rim struck upside down (president face up). These are not minting errors, but rather a variation created by the minting process. Such upside-down coins have been sold on auction websites like eBay and Amazon for greater than their face value, though they represent roughly 50% of the minted population. Stockpile and suspension of production By 2011, 1.4 billion uncirculated $1 coins were stockpiled, which, if laid flat, could reach from Los Angeles to Chicago. By 2016, this number might have reached two billion if the minting had continued unchanged. Rep. Jackie Speier of California circulated a "Dear Colleague" letter recommending that the U.S. not produce any dollar coins. She was planning to introduce legislation calling for the immediate halting of all dollar coin programs. The United States Government Accountability Office has stated that discontinuing the dollar bill in favor of the dollar coin would save the U.S. government about $5.5 billion over 30 years. On December 13, 2011, Vice President Joe Biden and Treasury Secretary Timothy Geithner announced that the minting of Presidential $1 coins for circulation would be suspended. Future entries in the program, beginning with those of Chester A. Arthur, would be issued in reduced quantities, only for collectors. The program's end and continuation The act specifies that for a former president to be honored, they must have been deceased for at least two years before issue. Hence, former presidents George H. W. Bush, Jimmy Carter, Bill Clinton, George W. Bush, and then-current president Barack Obama were ineligible to have a dollar coin issued in their honor when the series ended in 2016, after honoring Ronald Reagan, the last president who was eligible. Since the program has terminated, producing coins for those presidents not yet honored would require another Act of Congress. On February 12, 2019, Senator John Cornyn introduced a bill to authorize a Presidential dollar