.selectAll("text").attr("transform","rotate(90)").attr("x","10").attr("y","-3").attr("fill","#43662E").style("text-anchor","start").attr("font-family","calibri");//pone los años en vertical
labels.append("text").attr("transform","rotate(-90)").attr("fill","#43662E").attr("y",-80).attr("dy",".71em").attr("x",-80).style("text-anchor","end").attr("font-family","calibri").text("Número de nacimientos");