18–34 years old	35 years old or older	p-Value
February 2011
Phone	1.80%	2.20%	0.001***
Web	24.20%	15.40%	0.000***
Mail	73.90%	82.60%	0.000***
May 2011
Phone	1.70%	2.20%	0.000***
Web	23.80%	14.90%	0.000***
Mail	74.40%	82.70%	0.000***
July 2011
Phone	1.70%	2.50%	0.000***
Web	23.10%	14.60%	0.000***
Mail	75.10%	82.80%	0.000***
November 2011
Phone	1.68%	2.45%	0.000***
Web	23.12%	14.58%	0.000***
Mail	75.20%	82.97%	0.000***