Android : defining width and height to layouts android

my requirement is to make 10 layouts in a single layout . Each layout should be 50 % horizontally and 20% Vertically.

Current my code can make horizentally 50% but how to make same layouts to 20% vertical.

Can it be possible.

Code is

<LinearLayout android:layout_width="fill_parent"
android:layout_height="fill_parent" android:orientation="horizontal">

<LinearLayout android:layout_width="0dip"
    android:layout_height="wrap_content" android:orientation="horizontal"
    android:id="@+id/linearLayoutouter" android:layout_weight=".5"
    android:background="@android:color/holo_green_dark">

    <Button android:text="Button" android:id="@+id/button11"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"
        android:layout_gravity="center">
    </Button>

</LinearLayout>

<LinearLayout android:layout_height="wrap_content"
    android:id="@+id/linearLayout1" 
    android:orientation="vertical"
    android:layout_width="0dip" 
    android:layout_weight=".5"
    android:background="@android:color/holo_orange_light">
    <Button android:text="Button" 
        android:id="@+id/button1"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"
        android:layout_gravity="center">
    </Button>
    <Button android:layout_width="wrap_content" 
        android:id="@+id/button2"
        android:layout_height="wrap_content" 
        android:text="Button"
        android:layout_gravity="center"></Button>

</LinearLayout>