<md-input-container flex="50" class="selectQuitacao">
    <label>Ano</label>
    <md-select required ng-model="anosSelecionado">
        <md-option ng-value="a" ng-repeat="a in anos">{{a}}</md-option>
    </md-select>
</md-input-container>

<md-button class="md-primary md-raised" ng-click="imprimirQuitacao(anosSelecionado)">Imprimir</md-button>