New Jersey’s fastest growing town is also its youngest. The burgeoning population of Lakewood in Ocean County has a median age of just 18.4 among its nearly 134,000 residents. No other town comes close, recently released Census data shows. More than 1 in 10 residents in Lakewood are under the age of 5 and the median age is more than 46 years younger than the state’s oldest town, Weymouth Township in Atlantic County. MORE: These 39 N.J. towns have the oldest residents. See latest rankings.The second youngest town, New Brunswick, has a median age of 24 years old thanks in large part to Rutgers U…