dates <- seq(as.Date("2014-01-19"), length = 176, 
                                    by = "weeks")

bev_xts <- xts(bev, order.by = dates)

head(bev_xts[,"M.hi"], n = 3)

            M.hi
2014-01-19  458
2014-01-26  477
2014-02-02  539