code: function _showYearPicker(){
  
  		var oDate = this._getFocusedDate();
  		var oYearPicker = this.getAggregation("yearPicker");
  
  		if (oYearPicker.getDomRef()) {
  			// already rendered
  			oYearPicker.$().css("display", "");
  		} else {
  			var oRm = sap.ui.getCore().createRenderManager();
  			var $Container = this.$("content");
  			oRm.renderControl(oYearPicker);
  			oRm.flush($Container[0], false, true); // insert it
  			oRm.destroy();
  		}
  
  		this._showOverlay();
  
  		oYearPicker.setDate(oDate.toLocalJSDate());
  
  		if (this._iMode == 0) {
  			// remove tabindex from month
  			var oMonthsRow = this.getAggregation("monthsRow");
  
  			jQuery(oMonthsRow._oItemNavigation.getItemDomRefs()[oMonthsRow._oItemNavigation.getFocusedIndex()]).attr("tabindex", "-1");
  		}
  
  		_togglePrevNexYearPicker.call(this);
  		this._iMode = 1;
  	}
docs: Opens the year picker.
  This function assumes its called when a yearPicker aggregation is available, so the caller must take care for it.
  @private
  @returns {void}