How do I align an Android toolbar to the bottom of the screen?

I'm trying to put a toolbar I created at the bottom of the screen in my Android app. This is what I have so far:

http://ift.tt/1zJdP4x

I'm trying to move the black bar sitting there in the center at the bottom of the screen, but I can't figure out how to do it. This is the XML code I have in Android Studio so far:

<LinearLayout xmlns:android="http://ift.tt/nIICcg"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"

    >
    <!--Begin Top Bar-->
    <Toolbar
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Lbs"
            android:id="@+id/tvLbs"
            android:textSize="17dp"
            android:textColor="#000000"
            android:layout_gravity="left"/>

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:src="@drawable/logo"/>
        </Toolbar>

    <!--End Top Bar-->

    <ImageView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:src="@drawable/week1"
        />

    <!--Begin all scrollable stuff-->
    <ScrollView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">

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


            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/total"
                android:textSize="45dp"
                android:layout_gravity="center"
                android:id="@+id/tvDisplay"
                />

            <Button
                android:layout_width="250dp"
                android:layout_height="wrap_content"
                android:text="Add one"
                android:layout_gravity="center"
                android:textSize="20dp"
                android:id="@+id/bAdd"
                />

            <Button
                android:layout_width="250dp"
                android:layout_height="wrap_content"
                android:text="Subtract one"
                android:layout_gravity="center"
                android:textSize="20dp"
                android:id="@+id/bSubtract"
                />

        </LinearLayout>

    </ScrollView>

    <!--End Scrollable stuff-->

    <Toolbar
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="#000000"
        android:alignParentBottom="true">

        </Toolbar>

</LinearLayout>