high-profile and violent crimes against people who visited city nightclubs this year", mentioning the July 27 rape and murder of Jennifer Moore. One article discussed the dangers of police work and undercover investigations. In August 2006, the New York City Council started initiatives to correct the problems highlighted by the deaths of Moore and St. Guillen. There was also discussions about electronic I.D. scanners. Quinn reportedly threatened to revoke the licenses of bars and clubs without scanners. In September 2011, the NYPD Nightlife Association updated their Safety Manual Handbook. There is now a section on counterterrorism; this addition came after the planned terrorist attacks on certain bars and clubs worldwide. Administration Mayors Crime in New York City was high in the 1980s during the Mayor Edward I. Koch years, as the crack epidemic hit New York City, and peaked in 1990, the first year of Mayor David Dinkins's administration (1990–1993), but then began to decline; the number of murders fell from the 1990 peak to a level close to Koch's worst year of 1989 by Dinkins's final year of 1993. The decline accelerated dramatically during the first term of Mayor Rudolph Giuliani (1994–1997), the number of murders falling by sixty percent, and continued to decline, though at much slower rates, during both his second term (1998–2001) and Mayor Michael Bloomberg's three terms (2002–2013). Scholars differ on the causes of the precipitous decline in crime in New York City (which also coincided with a nationwide drop in crime which some have termed the "Great American Crime Decline"). In a 2007 paper, economist Jessica Reyes attributes a 56 percent drop in nationwide violent crime in the 1990s to the removal of lead (a neurotoxin that causes cognitive and behavioral problems) from gasoline. The Brennan Center for Justice has estimated that between 0% and 5% of the drop in crime in the 1990s may be attributed to higher employment; 5% to 10% of the drop may be attributed to income growth; and 0% to 10% of the drop from increased hiring of police officers. The Brennan Centre has also stated that the introduction of "compstat" procedures, being a combination of targeted enforcement at crime hot spots and the imposition of greater managerial accountability on police command staff, is the only tactic which has led clearly to subsequent reductions in crime. As law professor Lawrence Rosenthal reported, this was introduced during Giuliani's first term