Figure 2From: The evolution of mobile apps for asthma: an updated systematic assessment of content and toolsGrowth in numbers of asthma apps. Plot shows the total number of available apps for asthma against time, based on the original release date, for the period 2009 to mid-2013. Withdrawals are accounted for. Vertical lines indicate the dates of the 2011 and 2013 surveys. Data were not available for 5 apps; therefore, final n = 186.Back to article page