Crashing since last update

Hi,

Thanks for a great plugin, since the last update I am getting crash notifications, hetre is the stack trace

Error Details
=============
An error of type E_ERROR was caused in line 41 of the file /var/www/wordpress/wp-content/plugins/donation-thermometer/includes/therm_widget.php. Error message: Uncaught TypeError: number_format(): Argument #1 ($num) must be of type float, string given in /var/www/wordpress/wp-content/plugins/donation-thermometer/includes/therm_widget.php:41
Stack trace:
#0 /var/www/wordpress/wp-content/plugins/donation-thermometer/includes/therm_widget.php(41): number_format()
#1 /var/www/wordpress/wp-content/plugins/donation-thermometer/includes/therm_widget_setup.php(31): require_once('...')
#2 /var/www/wordpress/wp-admin/includes/template.php(1401): Thermometer_dashboard_widget::therm_widget()
#3 /var/www/wordpress/wp-admin/includes/dashboard.php(265): do_meta_boxes()
#4 /var/www/wordpress/wp-admin/index.php(203): wp_dashboard()
#5 {main}
  thrown

This seems to happen when entering the admin area. Disabling the plugin solves it (obviously!)

Thanks

The page I need help with: [log in to see the link]