PHP 5.3 version has reached EOL (end of life) in [august, 2014][php-53], PHP 5.4 is already at the phase of receiving security fixes only and will reach EOL next year (2015). Next major version of PHP 7 is already in development and is planned to be released in november, 2015. But the statistics of PHP version usage on servers is kind of shocking.
Thanks to the [research][pascal-martin] of PHP versions usage we have some data to work with. The majority of PHP servers has PHP 5.3 installed and also