Varies by race and nationality. Early onset male pattern baldness in East Asians is very very low, a fraction of a percent have visible hair loss before 30. It's higher among south Asians, blacks and highest among whites and Arabs. If say the latter category that maybe about 5% have progressed beyond NW2 by age 30. Even among whites, it's not common to be an NW3+ under 30. Anecdotally I'd say maybe 2% or so. Varies by country, think it's higher in the UK and Ireland than it is in France or Germany.