▁entities , ▁un ited ▁based ▁on ▁the ▁boundaries ▁of ▁the ▁pre - war ▁Br č ko ▁municipality , ▁with ▁the ▁Mayor ▁having ▁authority ▁over ▁the ▁entire ▁District . ▁ ▁List ▁of ▁May ors ▁ ▁Municip ality ▁of ▁Br č ko ▁( 1 9 9 5 – 2 0 0 0 ) ▁ ▁Br č ko ▁District ▁( 2 0 0 0 ▁– ▁present ) ▁ ▁See ▁also ▁Br č ko ▁Br č ko ▁District ▁International ▁Super visor ▁for ▁Br č ko ▁ ▁Notes ▁ ▁References ▁ ▁External ▁links ▁World ▁States men ▁– ▁Br č ko ▁ ▁Br cko ▁Category : Br č ko ▁District ▁Category : List s ▁of ▁may ors <0x0A> </s> ▁Ri ple y ▁County ▁is ▁the ▁name ▁of ▁two ▁count ies ▁in ▁the ▁United ▁States : ▁▁ ▁Ri ple y ▁County , ▁Indiana ▁ ▁Ri ple y ▁County , ▁Missouri <0x0A> </s> ▁The ▁ 7 7 4 – 7 7 5 ▁carbon - 1 4 ▁sp ike ▁is ▁an ▁observed ▁increase ▁of ▁ 1 . 2 % ▁in ▁the ▁concentration ▁of ▁carbon - 1 4 ▁is ot ope ▁in ▁tree ▁rings ▁dated ▁to ▁the ▁years ▁ 7 7 4 ▁or ▁ 7 7 5 ▁AD , ▁which ▁is ▁about ▁ 2 0 ▁times ▁as ▁high ▁as ▁the ▁normal ▁background ▁rate ▁of ▁variation . ▁It ▁was ▁discovered ▁during ▁a ▁study ▁of ▁Japanese ▁ced ar ▁trees , ▁with ▁the ▁year ▁of ▁occurrence ▁determined ▁through ▁d end ro chron ology . ▁A ▁sur ge ▁in ▁b ery l li um ▁is ot ope