项目添加到列表框时动画WPF数据模板？

<DataTemplate x:Key="ListBoxItemTemplate">
    <TextBlock Text="{Binding}" Margin="5">
        <TextBlock.Triggers>
           <EventTrigger RoutedEvent="TextBlock.Loaded">
               <BeginStoryboard>
                   <Storyboard>
                       <DoubleAnimation Storyboard.TargetProperty="Opacity" From="0" To="1" Duration="0:0:0.5"/>
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </TextBlock.Triggers>
    </TextBlock>
</DataTemplate>

<ListBox ItemTemplate="{StaticResource ListBoxItemTemplate}">
    <ListBoxItem>Item 1</ListBoxItem>
    <ListBoxItem>Item 2</ListBoxItem>
    <ListBoxItem>Item 3</ListBoxItem>
</ListBox>