Maraka Dasa is the period when the ruler is having lordship of 2nd and 7th houses in a horoscope. This will be greek and latin to you unless you are proficient in astrology.
Mercury and Saturn are Maraka dasas in your horoscope. Your current period is Saturn’s period which has started in 1999 and will be over in 2018. And you had the sub period of Mercury, another Maraka planet during 2002 to 2004 and nothing happened to you during that time. Is it not? You are still alive. So there is nothing to worry and you will live a long life of a Septuagenarian.
Do read my articles on this site as well as at http://navagrahastro.blogspot.in/ which will rid you of a lot of misgivings about Astrology.
Best of Luck.