year | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 | 2009 |
urban | 0.5362 | 0.5276 | 0.5089 | 0.4928 | 0.4896 | 0.4765 | 0.4580 | 0.4460 | 0.4319 |