How often do you have to use a tanning bed to be considered a "regular" user?

i have read that regular indoor tanning raises a persons risk of melanoma by 74 to 340%. in the past two years i'd say the number of times i have been tanning is between 2 and 6, not much at all. but i would like to go this week, just to develop a light to medium colored tan. im guessing i will have to go about 4 times to get the color i want. keep in mind i have never made a serious habit of this, nor could i afford to even if i wanted to. i would just like to know how often my use of tanning beds would compare to a regular users.