It will take exactly $N_1$ years for the value in your current portfolio to double at $5\%.$ If we use the rule of $70,$ at $5\%,$ it will take $N_2$ years. What is $N_1-N_2$ rounded to $2$ decimal places?

$0\mathrm{.}09$

$0\mathrm{.}00$

$0\mathrm{.}45$

$0\mathrm{.}96$